Abstract:
This research explores the frictional and wear characteristics of conventional and additively manufactured personalized joint implants through advanced optical methods. The focus is on analysing lubricant film formation and its impact on the performance of hip and knee replacements, as well as small joint implants produced via 3D printing.

Main objectives:

• To elucidate the lubrication mechanisms in hip and knee joint replacements.

• To characterize the lubrication and wear behaviour of 3D-printed small joint implants.

• To develop optimized friction surfaces for 3D-printed segmental joint replacements.

Research content:
This research utilizes custom-designed simulators tailored specifically for hip and knee joint experiments, combined with advanced optical techniques, including colorimetric interferometry and fluorescence microscopy, enabling detailed analyses of lubricant film formation and wear characteristics. A significant breakthrough of this study was the first-ever analysis of lubricant film thickness in artificial hip joints, considering for the real conformity of articulating surfaces, when focusing on the effect of the material properties, diameter clearance of the replacement, and the composition of synovial fluid. Another pioneering aspect of this research is the experimental examination of lubricant film formation mechanisms on both condyles of knee replacements.

The research has also successfully applied 3D optical scanning methods to evaluate the volumetric wear of explanted artificial hip pairs, yielding valuable data on long-term implant performance. Building on these findings, the research is expanding into the innovative field of 3D printing for small joint implants and segmental (local) joint replacements. Here, the focus is on analysing friction surfaces of biomaterials specifically designed for additive manufacturing, such as the Ti6Al4V alloy, with the goal of enhancing the durability and functionality of these implants. This ongoing work aims to optimize the design and production of 3D-printed implants, potentially revolutionizing the approach to joint replacement surgery.

Publications:
NEČAS, D.; VRBKA, M.; URBAN, F.; GALLO, J.; KŘUPKA, I.; HARTL, M. In situ observation of lubricant film formation in THR considering real conformity: The effect of diameter, clearance and material. Journal of the mechanical behavior of biomedical materials, 2017, vol. 69, no. 5, p. 66-74. ISSN: 1751-6161.
https://doi.org/10.1016/j.jmbbm.2016.12.018

NEČAS, D.; VRBKA, M.; MARIAN, M.; ROTHAMMER, B.; TREMMEL, S.; WARTZACK, S.; GALANDÁKOVÁ, A.; GALLO, J.; WIMMER, M.; KŘUPKA, I.; HARTL, M. Towards the Understanding of Lubrication Mechanisms in Total Knee Replacements – Part I: Experimental Investigations. Tribology International, 2021, vol. 156, no. 4, p. 106874-106874. ISSN: 0301-679X. https://doi.org/10.1016/j.triboint.2021.106874

ODEHNAL, L.; RANUŠA, M.; VRBKA, M.; KŘUPKA, I.; HARTL, M. Tribological Behaviour of Ti6Al4V Alloy: An Application in Small Joint Implants. Tribology Letters, 2023, vol. 71, no. 4, p. 125-125. ISSN: 1023-8883. https://doi.org/10.1007/s11249-023-01795-4

Partners and Collaboration:
Olomouc University Hospital, Zdravotníků 248/7, 779 00 Olomouc, Czech Republic.

ProSpon spol. s r. o., Jiřího Voskovce 3206, 272 01 Kladno, Czech Republic.

RUSH University, 600 S. Paulina St., Chicago, Illinois 60612, USA.

Friedrich-Alexander-Universitat Erlangen-Nürnberg (FAU), Martensstrasse 9, 910 58, Erlangen, Germany.

Projects:
The influence of joint fluid composition on formation of lubricating film in THA, The Ministry of Health, NT14267, 2013-2015.

The effect of tribological processes on the durability of knee joint replacements, Ministry of Education, Youth and Sports – INTER-EXCELLENCE – Subprogramme INTER-ACTION, LTAUSA17150, 2017-2020.

Friction and lubrication of small joint implants produced by 3D metal printing additive technology, Czech Science Foundation – Standard projects, 22-02154S, 2022-2024.

Contact person:
prof. Ing. Martin Vrbka, Ph.D.